The fashionable theme, the go. The Crack Lay, of late is used, in the cant language, to signify the art and mystery of house-breaking.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
To Crack * CrackerNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes